1. Field of the Invention
This invention relates to a jacket for a floppy disk. This invention particularly relates to a jacket colored in a color other than black.
2. Description of the Prior Art
Flexible disks referred to as floppy disks or diskettes comprise a case (hereinafter referred to as the jacket) fabricated by folding a sheet of a plastic material such as polyvinyl chloride (PVC), polycarbonate or polyethylene terephthalate (PET) or bonding such sheets in bag form, and a disk-like magnetic recording medium (hereinafter referred to as the disk) rotatably housed in the jacket and composed of a flexible substrate made of PET or the like and a magnetic recording layer or layers overlaid on one or both surfaces of the substrate. The flexible disks are widely used as magnetic recording media for computers and word processors.
Liners such as nonwoven fabrics are overlaid on the inner surfaces of the jacket for protecting the disk, decreasing the rotation torque of the disk, and cleaning the disk surfaces. Carbon has been added to the jacket as a conductivity imparting agent for preventing static electricity from arising during recording, reproducing and handling of the flexible disk. When static electricity arises on the flexible disk, dust adheres thereto, drop-outs arise during recording and reproducing, and the disk surfaces are scratched. Therefore, it has been necessary to decrease the electric resistance of the jacket by the addition of carbon.
Addition of carbon to the flexible disk jacket material colors the jacket black. The conventional jacket has a black outer surface since it contains carbon and no other color pigment.
The black jacket is disadvantageous in that fingerprints are readily perceptible thereon. Therefore, in order to make the fingerprint imperceptible, the black jacket is normally embossed. As a result, the jacket production process becomes complicated. Even then it it not always possible to make fingerprints on the black jacket sufficiently imperceptible by embossing.
In order to eliminate the drawbacks of the black jacket, the inventors studied development of a jacket which is colored in a color other than black.
Coloring of the jacket is achieved by adding a color pigment to the jacket material (plastic sheet). However, the colored jacket has drawbacks in that light transmittance becomes higher than with the black jacket and that the light resistance, i.e. the resistance of the color to deterioration over time caused by light, becomes low.
Normally, the jacket is provided with a write enabling notch and an index window detected by a light sensor in the disk drive unit so that writing, reading and erasing of information on the disk housed in the jacket are conducted correctly. When the light transmittance increases at sections other than those provided with the write enabling notch and the index window, there arises the risk of the light sensor mechanism malfunctioning. Therefore, the light transmittance must be decreased to conduct information recording correctly.
Also, since the jacket is generally stored or repeatedly used over long periods, it should exhibit sufficient light resistance so that the color is not deteriorated readily.